Various types of printers have been developed for printing data contained in or treated by a computer. The printers apply characters to paper or other types of data recording carriers in response to signals from the computer. The printers include systems for guiding the paper and controlling the motion of the print head across the sheet. The print systems are frequently distinguished as mechanical printers and electrostatic or xerographic printers.
This type of printer usually includes means for determining the location of the print head to permit an exact automatic adjustment of the head at a point where it is desired to print a character. Printers are known in which potentiometric systems detect printer head location. Sensors of the potentiometric systems are connected to a position servo-controlling module which controls a motor for driving the printing head. However, such systems do not always prove to be sufficiently accurate and are incapable of relatively high speed servo-control. This is particularly disadvantageous in high speed dot printers in which different characters are formed by relatively high speed striking of a set of points which together define each character.
An object of the present invention is to provide a new and improved system for detecting print head location very accurately and easily without being very cumbersome.